Heavy duty, commercial brush cutters have been used in connection with forestry management, right-of-way clearing and maintainance, and for similar purposes. These brush cutters are typically heavy steel rotary circular blades that are mounted on tracked or rubber-tired vehicles. The brush cutter blade is typically powered hydraulically. An exemplary prior art blade may be six feet in diameter, weigh several hundred pounds, and contain upper and lower cutting teeth. Such a blade can thus cut brush from its upper and lower surfaces as well as its periphery.
Cutter blades of such a size build up substantial momentum during operation and can easily snag a log or limb and hurl it a great distance. To minimize the hazzard of operating or being in the vicinity of this type of cutter blade, some brush cutters have incorporated a protective shroud. These shrouds leave only part of the blade exposed so that peripheral cutting can occur. However, the shroud can become plugged with a log or limb that is picked up by the cutter blade and wedged between the blade and the shroud. The resulting impact force on the shroud and on the blade-mounting apparatus can cause significant damage to these parts up to and including a breakdown.